[Image above] The long-range backscatter system uses a source that emits a radio signal, low-power sensors that encode information in reflected signals, and an off-the-shelf receiver. Credit: Dennis Wise; University of Washington
Research has come a long way in the development of small electronics that can capture anything from medical conditions to fitness levels. But, due to the low power on which they operate, collecting data from these devices has been limited to a smartphone or other electronic device located in close proximity to the original data-generating mechanism.
In other words, the further away communicating devices are from one another, the more battery power they need in order to “talk”. So if you want to connect devices to communicate with one another over long distances, you would need large batteries—which defeats the purpose of using small electronic devices to begin with.
But a team of engineers at the University of Washington has recently broken through this barrier with the development of a long-range (LoRa) backscatter system that uses very little power. Backscatter is a low-cost way to transmit signals through low power without using conventional radio technology.
“Until now, devices that can communicate over long distances have consumed a lot of power,” Shyam Gollakota, lead faculty and associate professor in the Paul G. Allen School of Computer Science & Engineering says in a UW news release. “The tradeoff in a low-power device that consumes microwatts of power is that its communication range is short.”
The researchers built prototypes for a contact lens and a flexible epidermal patch and then used their LoRa backscatter system to transmit information over a 3,300-ft2 room. According to the researchers, that distance is much longer than the range of other smart contact lenses.
They also successfully used the LoRa backscatter system to communicate over a one-acre farm and a 4,800-ft2 house.
This flexible patch successfully collected and transmitted medical data across 3,300 ft2. Credit: Dennis Wise; University of Washington
The system consists of three different parts: a radio signal source, encoding sensors, and a receiver that decodes the information. Putting the sensor between the signal source and receiver enables data to be transmitted at a distance of up to nearly one-third of a mile (475 m). But placing the sensor close to the signal source enables data to be transmitted as far away as 1.7 mi (2.8 km).
But LoRa backscatter has its limitations. One of the problems the team encountered was an inability to recognize the signal and differentiate it from other noise.
“It’s like trying to listen to a conversation happening on the other side of a thick wall,” doctoral student Mehrdad Hessar says in the release. “You might hear some faint voices, but you can’t quite make out the words.”
They solved this by incorporating chirp spread spectrum, which spreads signals across multiple frequencies. According to the release, the process enabled the team “to achieve much greater sensitivities and decode backscattered signals across greater distances even when it’s below the noise.”
The research team has already formed a startup, Jeeva Wireless, to bring their system to market—which they anticipate to be early 2018.
This breakthrough could give the medical and wearable device industries a much-needed boost in their ability to expand product lines and improve capabilities. And because the researchers expect the cost of the sensors to be $0.10–$0.20 each, farmers could use them in their fields to monitor seed growth and soil temperature.
According to the team’s paper, the research enables “wide area connectivity for everyday objects and opens applications in domains like smart cities, precision agriculture, industrial, medical and whole-home sensing, where backscatter is currently infeasible.”
“This is the first wireless system that can inject connectivity into any device with very minimal cost,” Vamsi Talla, one of the researchers, states.
The paper, published online in ArXiv, is “LoRa backscatter: Enabling the vision of ubiquitous connectivity.”
Learn more about the system in the video below.
Credit: UW (University of Washington); YouTube
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